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최지용,조안태,김광용,Choi Ji-Yong,Cho An-Tai,Kim Kwang-Yong 한국유체기계학회 2006 한국유체기계학회 논문집 Vol.9 No.4
In the present work, characteristics of the flow in the cage of a steam turbine bypass control valve for thermal power plant are investigated. Experimental measurement for wall static pressure has been carried out to validate numerical solutions. And, the flowfield is analyzed by solving steady three-dimensional Reynolds-averaged Navier-Stokes equations. Shear stress transport (SST) model is used as turbulence closure. The effects of the flow area between stages of the cage on the pressure drop are also found.
최지용,신은성 ( Ji Yong Choi,Eun Sung Shin ) 한국물환경학회 1997 한국물환경학회지 Vol.13 No.4
To assist in the dissemination of water quality information to expert as well as layman, Korea Water Quality Index(K-WQI) has been developed. The K-WQI is based on ten physico-chemical and biological determinants which were adopted by an intensive interview and questionnaire survey, and a review of water quality criteria. The sub-index is developed by use of both opinion research and mathematical techniques. The former involves the completion of a series of questionnaires by a panel of water experts thus facilitating the objective selection, transformation and weighting of determinants. The latter involves the use of regression for the construction of the sub-index functions. Aggregation for sub-index is used weighted product function. The weighted product, when applied to decreasing scale subindices, does not exhibit eclipsing. Application of the K-WQI to water quality data, drawn from a selection of Korean river reaches typifying a range of river qualities, has shown that the Index not only act as indicators of water quality change, but can also indicate the effects of these changes on potential water use.
최지용,박원규,이상일,Choi, Ji-Yong,Park, Won-Kqyu,Lee, Sang-Il 한국수자원학회 1996 물과 미래(한국수자원학회지) Vol.29 No.2
하천 및 호소수 수질의 온라인 계측을 위한 수질자동측정망의 설계에서 측정위치와 항목의 선정은 전체시스템의 성능을 결정짓는 중요한 인자이다. 본 논문에서는 상수원유역의 상시수질감시 및 사전경보 기능을 갖는 측정망의 구축이 측정위치와 항목을 결정하는 방법을 연구하였다. 측정위치를 결정하기 위한 선정기준은 상수취수량과 고정오염원의 위치를 바탕으로 대상지역에 대한 거시적 후보지점을 선정한 뒤, 구체적인 지점은 오염물질 유하거리를 기준으로 단계적으로 결정한다. 측정항목은 유역의 오염특성과 수질오염사고 이력을 참고하되, 경제적인 측면을 고려하여 필수측정항목과 선택항목으로 나누어 위치별로 달리하는 방안을 제시하였다. 제안방법을 낙동강유역에 적용함으로써 측정망 구성과정을 예시하였다. In designing automatic water quality monitoring networks for a river basin, determination of measurement locations and items is critical to the effectiveness of the total system. In this paper we studied how to decide these two design factors when a monitoring network is designed for the purposse of water quality surveillance and emergency alarm. For measurement locations, candidate sites are chosen based on the intake amount for water supply and the point sources of contamination. Then, detailed locations are decided according to the contaminant flow distance. As for measurement items, characteristics and the accident history of water pollution in the basin must be taken into account. Considering economic aspects, we proposed a two-stage measurement plan: basic components for all locations and selective ones variable for different locations. Proposed methodology is demonstrated through a case study for Nak-dong River Basin.
최지용(Ji-Yong Choi) 경기연구원 2006 경기논단 Vol.8 No.3
Recently, turbidity problem occurring in many lakes is regarded as a serious problem in the upper Han river basin. Turbidity exceeding a constant level causes aesthetic problem, drops value as water resources, and gives a bad influence to waterbodies and surrounding ecosystem. It is very urgent to look for the fundamental causes of long term influence by turbidity in multipurpose dams, and to get measures about it. Korea Government is executing basic investigation about turbidity for many years and measures to solve the problems. These measures can be categorized to “measures in a lake”, “downstream measures” and “measures through watershed management”. The first and the second correspond to “measures after influx” and the last one is included in “measures before influx”. A preventive technique through watershed management is thought as the most effective measure when taking into consideration both in water quality and quantity management aspect including nonpoint source. Therefore, this study focused on “measures before influx” and tried to propose an efficient management toward turbidity control. As the objective of the study, we chose Soyang dam, where turbidity is becoming a problem because of its long detention time. Once a turbidity problem occurs in a multipurpose dam, its management becomes very difficult, therefore, turbidity management must focus finally on “measures before influx”. For this, we have to approach to the problem with both “upstream management” and “system improvement”.
최지용(Ji-Yong Choi),김광용(Kwang-Yong Kim) 한국유체기계학회 2005 유체기계 연구개발 발표회 논문집 Vol.- No.-
In the present work, characteristics of the flow in CAGE of a steam turbine LP/HP Bypass control valve for thermal power plant are investigated. The flow field is analyzed numerically by solving steady three-dimensional Reynolds-averaged Navier-Stokes equations. Shear stress transport (SST) model is used as turbulence closure.